Does Coke Really Dehydrate you?

[soop]

I was arguing with a bunch of friends the other day. The question is: does coke dehydrate you?

My definition of ‘dehydration’ is: it has a negative effect on the total amount of water in your body.

Another way of posing the question is: If kept drinking coke, would you die of thirst?

If coke does indeed dehyrate you, what is the mechanism behind this dehydration?

The straight dope on this matter is urgely needed!

[barbitu8]

Coke has a lot of sugar and it takes water to digest this sugar. Consequently, you drink pop (not necessarily Coke), feel like you’ve quenched your thirst, but that’s only the immediate feeling. After a short while, you’re feel thirsty again, as water is used up to digest the sugar. I have no stats, but I feel that this is a losing proposition.

[friedo]

Coke also contains lots of caffeine, a diuretic, (increases urination.)

[Blake]

By the definition of dehydration “has a negative effect on the total amount of water in your body” the answer is an indisputble 'NO".

Caffeine isn’t a very good diuretic, nowhere near good enough to cause dehydration. As Snopes says (http://www.snopes.com/toxins/water.htm ) :

*Regular coffee and tea drinkers become accustomed to caffeine and lose little, if any, fluid. In a study published in the October issue of the Journal of the American College of Nutrition, researchers at the Center for Human Nutrition in Omaha measured how different combinations of water, coffee and caffeinated sodas affected the hydration status of 18 healthy adults who drink caffeinated beverages routinely.

“We found no significant differences at all,” says nutritionist Ann Grandjean, the study’s lead author. “The purpose of the study was to find out if caffeine is dehydrating in healthy people who are drinking normal amounts of it. It is not.”

The same goes for tea, juice, milk and caffeinated sodas: One glass provides about the same amount of hydrating fluid as a glass of water. The only common drinks that produce a net loss of fluids are those containing alcohol – and usually it takes more than one of those to cause noticeable dehydration, doctors say.”
*

Sugar doesn’t take water to digest. Sugar is a carbohydrate and and carbohydrates produce water as a result of digestion. They don’t use it. It’s true that digestion causes an increase in respiration and body temperature that will cause a little more water to be lost, but that’s near enough perfectly balanced by the water the body produces form the sugar.

In other words Coke isn’t dehydrating. It’s probably not quite as efficient at hydration as pure water or Gatorade, but there’s no way that it can possibly do anything except hydrate.

[Qadgop_the_Mercotan]

I wrote a nice little post, but I see that Blake is right on the money, so my contribution is irrelevant. Way to go Blake.

QtM, MD

[SandWriter]

Hey Soop,

Welcome to the straight dope. It’s a great place to learn the facts. Another place to learn about urban legends that have been circulating around the internet for years and years is the home page of Blake’s link. In fact, they have an entire section on Coca-Cola myths.

You can read up on it and win some more bets with your friends.
-Sandwriter

[asterion]

Also, caffeine, if I remember Intro Bio correctly, acts by supressing ADH–anti-diuretic hormone. ADH is what tells your kidneys what to do with the water and salt gradients. Anyway, that’s why Coke is a mild diuretic.